Cold gas-dynamic spraying (hereinafter “cold spraying”) is a technique that is sometimes employed to form coatings of various materials on a substrate. In general, a cold spraying system uses a pressurized carrier gas to accelerate particles through a nozzle and toward a targeted surface. The cold spraying process is referred to as a “cold gas” process because the particles are mixed and sprayed at a temperature that is well below their melting point, and the particles are near ambient temperature when they impact with the targeted surface. Converted kinetic energy, rather than a high particle temperature, causes the particles to plastically deform, which in turn causes the particles to form a bond with the targeted surface. Bonding to the component surface occurs as a solid state process with insufficient thermal energy to transition the solid powders to molten droplets. Cold spraying techniques can therefore produce a wear or corrosion-resistant coating that strengthens and protects the component using a variety of materials that can not be applied using techniques that expose the materials and coatings to high temperatures.
The nozzle used for cold spraying is typically designed to receive particles that are sized between about 5 and about 50 microns and accelerated to supersonic speeds. In most cases, the nozzle is a straight, rectangular tube that defines a relatively straight flowpath along which the particles follow. The nozzle also typically includes an outlet through which the particles exit at a velocity ranging between 300 and 1200 m/s. To create a coating having optimal properties, the particles are preferably sprayed at a 90 degree angle relative to the component surface; thus, the nozzle is disposed at a substantially 90 degree angle relative to the surface during cold spraying as well.
Although conventionally designed nozzles are useful for cold spraying many different component surface configurations, they may not be as useful in certain circumstances. For example, the cold spray process may not be employed to repair worn surfaces of certain bores that are formed in a component. Specifically, the bore may have a diameter that is smaller than the length of the nozzle so that the nozzle may not be placed at a 90 degree angle relative to the bore surface.
Thus, there is a need for a nozzle that may be used with a cold spray system for repairing any surface of a component. More particularly, there is a need for a nozzle that can be used to repair a worn surface of a bore that may be formed in the component. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.